Port extended status extension to v3 API Part 1

This changeset only copies the v2 implementation file into the
appropriate v3 directory unchanged. The copy as-is will not be
loaded by either the v2 or v3 extension loaders. The second
changeset will then make the changes required for it to work as a
v3 extension.

This is being done in order to make reviewing of extension porting
easier as gerrit will display only what is actually changed for v3
rather than entirely new files.

Partially implements blueprint nova-v3-api

Change-Id: Ia5b80b70a7a459bf973de1c1aea8dc650e763b8d
Merge "Port extended status extension to v3 API Part 1"